Silicone-based barrier compositions

ABSTRACT

A liquid applied, silicone-based air and water barrier coating composition and its use as a silicone-based air and water barrier is provided. The barrier is generally vapour permeable and suitable for the construction industry. The liquid coating composition generally has a shelf-life of at least 15 months. The liquid coating composition comprises: (i) a crosslinked polysiloxane dispersion comprising (c) a surfactant and (d) water; (ii) one or more rheology modifiers in an amount of from 0.25 to 5 wt. % of the composition; and (iii) an acidic pH stable colloidal silica in an amount of from 15 to 30 wt. % of the composition; and optionally (iv) one or more stabilizers.

TECHNICAL FIELD

This disclosure relates to a liquid applied, air and water barriercoating composition for use as a liquid, silicone-based air and waterbarrier, which is preferably vapour permeable for the constructionindustry, which silicone-based air and water barrier has a shelf-life ofgreater than or equal to (≥) 15 months.

BACKGROUND

A wide variety of air and water barrier systems are used in both newbuilding and remedial construction applications. They are designed toeliminate uncontrolled water leakage through e.g. exterior walls and/orfacades enabling the control of e.g. temperature, humidity levels,moisture levels and air quality throughout a building therebyminimising, for example, the possibility of damp problems and/or thechance of mold growth and poor air quality.

Water barriers are intended to minimise or exclude the ingress of liquidwater into a building through a wall or façade or the like e.g. viacapillary action through cracks, holes or porous materials. Theapplication of such barrier systems to constructions, e.g. cavity wallsystems, results in energy cost savings especially if the water barriersare also air barriers in which case they may also significantly reducethe ingress of airborne pollutants by substantially reducing the amountof air leakage through the exterior walls or facades of a building. Airbarriers reduce air flow through building wall assemblies improvingenergy efficiency.

A liquid applied, silicone-based air and water barrier is preferablydesigned to be (water) vapour permeable i.e. to control the amount of(water) vapour diffusing through a wall due to variable vapourpressures. Unless prevented or controlled, water vapour will naturallymove from a high concentration to a lower concentration until it is inbalance. Hence, if the vapour pressure is high outside the wall and lowinside the wall, vapour will be directed inward (and vice versa).

The use of aqueous based sprayable silicone elastomeric coatings as airbarriers for walls and facades or the like in buildings based onsilicone waterborne emulsions (SWBE) are highly desirable in theconstruction industry (in contrast to solvent borne systems) becausethey are both VOC (volatile organic compound) free and arenon-reactive/non-cure systems. Furthermore, unlike many organic coatingssilicone-based coatings have excellent UV stability. Hence, whereasexternally applied organic coatings cannot be exposed to UV radiationfor extended periods of time during construction without necessitatingre-application of one or more additional coating layer(s) whilst no suchrequirement is necessary for silicone-based coating compositions.Silicone-based coating compositions may be of much lower viscosity thanorganics which enables the use of a larger variety of applicatorsincluding even standard low-cost commercial paint sprayers asapplicators and the resulting coatings have the significant advantageover organic based coating of being compatible with other silicone-basedmaterials used in the construction industry such as caulks, adhesives,and weather sealants, avoiding the need to apply compatiblising layersof adhesives, primers and/or adhesion promoters and the like at jointsbetween air and water barriers and said silicone caulks, adhesives andweather sealants.

However, one problem that remains to be solved with the aforementionedSWBE type coating compositions used for these applications is shelf lifestability which remains an issue even when the composition contains oneor more rheology modifiers. Rheology modifiers are traditionally used toboth control how coating compositions flow when spray or roll/brushapplied to achieve uniform coating without sagging and also thickencompositions during storage preventing separation of the components dueto gravity driven separation.

This problem is not helped by the recent increasing interest in the useof colour tinted coating compositions which dry or cure to colour tintedcoatings for reasons of architectural aesthetics. The use of such colourtinted coatings provides improved “hiding” of underlying components ofthe building with e.g. grey tinted systems being preferred to white asthese are less likely to be visible through gaps in the final exteriorsurface (cladding/siding). However, whilst it would be desirable to useaqueous dispersions of pigments as tinting components rather thanpowdered pigments at either the manufacturing plant or at point of usedue to ease of use, previous commercial air and/or water barriers basedon SWBEs have been either untinted or tinted with powders (leading todifficulties with retail-based tinting). This is because, unfortunately,the aqueous dispersants of pigments and colorants e.g. carbon black areknown to have a destabilizing impact on the aforementioned SWBEcompositions leading to rapid loss of shelf-life. Even the presence ofpreferred rheology modifiers, such as, for example, hydrophobicallymodified alkali swellable emulsions (HASEs) and other associativethickener type rheology modifiers, does not prevent gelation fromoccurring after only about 6 months at room temperature resulting inboth untinted and tinted compositions being considered shelf-lifeconstrained because of the limitations in supply chain options,geographic distribution, production scheduling, and ultimately coatingperformance.

SUMMARY OF INVENTION

It has been surprisingly identified that the introduction of an acidicpH stable colloidal silica in a liquid applied, air and water barriercoating composition provides an unforeseen benefit in that its presencein the compositions appears to overcome previous shelf-life issueswherein historically such compositions rarely had shelf-lives of greaterthan 6 months but in the presence of the acidic pH stable colloidalsilica the shelf life thereof can be extended to greater than or equalto (>) 15 months.

There is provided herein a liquid applied, air and water barrier coatingcomposition comprising:

(i) a crosslinked polysiloxane dispersion of: a reaction product of (a)a siloxane polymer having at least two —OH groups per molecule, orpolymer mixture having at least two —OH groups per molecule, having aviscosity of between 5000 to 500,000 mPa·s at 21° C. and (b) at leastone self-catalyzing crosslinker reactive with (a), and additionallycomprising (c) a surfactant and (d) water;(ii) one or more rheology modifiers in an amount of from 0.25 to 5 wt. %of the composition,(iii) an acidic pH stable colloidal silica in an amount of from 15 to 30wt. % of the composition; and optionally(iv) one or more stabilizers.The liquid applied, air and water barrier coating composition ispreferably (water) vapour permeable.

For the avoidance of doubt, in general colloidal silica particles arestable in between pH 2-4 and at pH greater than (>)8.0 and unstable inthe pH range 3 to 7. The term “an acidic pH stable colloidal silica istherefore intended to mean throughout this disclosure a colloidal silicagrade that is stable across the entire pH range of 2-11.

There is also provided herein a wall assembly having an internal sideand an external side, wherein either or both said internal side and saidexternal side is coated with a dried coating of the liquid applied, airand water barrier coating composition as hereinbefore described. Thedried coating is preferably (water) vapour permeable, alternatively thedried coating is (water) vapour permeable.

There is also provided herein a method for increasing the shelfstability of a liquid applied, air and water barrier coating compositionby introducing (iii) an acidic pH stable colloidal silica in an amountof from 15 to 30 wt. % of the composition; into a liquid applied, airand water barrier coating composition otherwise comprising

(i) a crosslinked polysiloxane dispersion of: a reaction product of (a)a siloxane polymer having at least two —OH groups per molecule, orpolymer mixture having at least two —OH groups per molecule, having aviscosity of between 5000 to 500,000 mPa·s at 21° C. and (b) at leastone self-catalyzing crosslinker reactive with (a), and additionallycomprising (c) a surfactant and (d) water;(ii) one or more rheology modifiers in an amount of from 0.25 to 5 wt. %of the composition, and optionally

(iv) one or more stabilizers.

There is also provided herein a method of treating a wall assembly,having an internal side and an external side, on either or both of saidinternal side and/or said external side with a liquid applied, air andwater barrier coating composition as herein described by spraying,brushing, or rolling.

There is also provided herein a use of an acidic pH stable colloidalsilica (iii) in an amount of from 15 to 30 wt. % of the composition; forincreasing the shelf stability of a liquid applied, air and waterbarrier coating composition otherwise comprising

(i) a crosslinked polysiloxane dispersion of: a reaction product of (a)a siloxane polymer having at least two —OH groups per molecule, orpolymer mixture having at least two —OH groups per molecule, having aviscosity of between 5000 to 500,000 mPa·s at 21° C. and (b) at leastone self-catalyzing crosslinker reactive with (a), and additionallycomprising (c) a surfactant and (d) water;(ii) one or more rheology modifiers in an amount of from 0.25 to 5 wt. %of the composition, and optionally

(iv) one or more stabilizers.

DESCRIPTION

This disclosure relates to a liquid applied, air and water barriercoating composition comprising a silicone water borne emulsion(hereafter referred to as SWBE) having a shelf-life of ≥15 months. Theextended shelf-life is achieved using an acidic pH stable colloidalsilica. It has been unexpectedly found that when an acidic pH stablecolloidal silica is used, in a specific range, in combination with oneor more rheology modifiers, in a liquid applied, air and water barriercoating composition as hereinbefore described, said composition has ashelf-life of greater than or equal to (≥) 15 months, which issignificantly greater than the approximately 6 months of priorcompositions.

The improved shelf life is potentially commercially significant given itprovides a means of increasing the shelf life of untinted and/or tintedliquid applied, air and water barrier coating compositions, therebyremoving at least some of the constraints and limitations on supplychain options, geographic distribution, production scheduling, andultimately coating performance.

The liquid applied, air and water barrier coating composition ashereinbefore described has shelf-life stability which corresponds togreater than or equal to (≥) 15 months at room temperature and therebyprovides:—

1) effective stabilization of the formulations for ≥15 months,2) the opportunity for point of sale tinting with aqueous dispersions,if required and3) the opportunity for point of manufacture tinting with aqueousdispersions; whilst maintaining its air and water barrier properties.

The liquid applied, vapour permeable, air and water barrier coatingcomposition comprises:

(i) a crosslinked polysiloxane dispersion of: a reaction product of (a)a siloxane polymer having at least two —OH groups per molecule, orpolymer mixture having at least two —OH groups per molecule, having aviscosity of between 5000 to 500,000 mPa·s at 21° C., and (b) at leastone self-catalyzing crosslinker reactive with (a), and additionallycomprising (c) a surfactant and (d) water.

The siloxane polymers or polymer mixtures (a) used as starting materialsfor the reaction product (i) above have a viscosity between 5,000 to500,000 mPa·s. at 21° C. using a recording Brookfield viscometer withSpindle 3 at 2 rpm according to ASTM D4287-00(2010). The siloxanepolymers are described by the following molecular Formula (1)

X_(3-n)R_(n)—YO—(R¹ ₂SiO)_(z)—Y—R_(n)X_(3-n)  (1)

where n is 0, 1, 2 or 3, z is an integer from 500 to 5000 inclusive, Xis a hydrogen atom, a hydroxyl group and any condensable or anyhydrolyzable group, Y is a Si atom or an Si—(CH₂)_(m)—SiR¹ ₂ group, R isindividually selected from the group consisting of aliphatic, alkyl,aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl or aromatic aryl groupsand R¹ is individually selected from the group consisting of X,aliphatic, alkyl, alkenyl and aromatic groups and m is an integerbetween 1 and 12 inclusive, alternatively between 1 and 10 inclusive,alternatively between 1 and 6 inclusive.

The siloxane polymer (a) can be a single siloxane represented by Formula(1) or it can be mixtures of siloxanes represented by the aforesaidformula or solvent/polymer mixtures. The term “polymer mixture” is meantto include any of these types of polymers or mixtures of polymers. Asused herein, the term “silicone content” means the total amount ofsilicone in the dispersed phase of the dispersion, from whatever source,including, but not limited to the silicone polymer, polymer mixtures,self-catalytic crosslinkers and when present, fillers, in-situ resinreinforcers and stabilizers.

Each X group may be the same or different and can be a hydrogen atom,hydroxyl group and any condensable or hydrolyzable group. The term“hydrolyzable group” means any group attached to the silicon which ishydrolyzed by water at room temperature. The hydrolyzable group Xincludes hydrogen atom, halogen atoms, such as F, Cl, Br or I; groups ofthe Formula —OT, where T is any hydrocarbon or halogenated hydrocarbongroup, such as methyl, ethyl, isopropyl, octadecyl, allyl, hexenyl,cyclohexyl, phenyl, benzyl, beta-phenylethyl; any hydrocarbon etherradical, such as 2-methoxyethyl, 2-ethoxyisopropyl, 2-butoxyisobutyl,p-methoxyphenyl or —(CH₂CH₂O)₂CH₃; or any N,N-amino radical, such asdimethylamino, diethylamino, ethylmethylamino, diphenylamino ordicyclohexylamino. X can also be any amino radical, such as NH₂,dimethylamino, diethylamino, methylphenylamino or dicyclohexylamino; anyketoxime radical of the formula —ON═CM₂ or —ON═CM′ in which M is anymonovalent hydrocarbon or halogenated hydrocarbon radical, such as thoseshown for T above and M′ is any divalent hydrocarbon radical, bothvalences of which are attached to the carbon, such as hexylene,pentylene or octylene; ureido groups of the formula —N(M)CONM″₂ in whichM is defined above and M″ is hydrogen atom or any of the above Mradicals; carboxyl groups of the formula —OOCMM″ in which M and M″ aredefined above or carboxylic amide radicals of the formula —NMC═O(M″) inwhich M and M″ are defined above. X can also be the sulphate group orsulphate ester groups of the formula —OSO₂(OM), where M is as definedabove; the cyano group; the isocyanate group; and the phosphate group orphosphate ester groups of the formula —OPO(OM)₂ in which M is definedabove.

The most preferred X groups are hydroxyl groups or alkoxy groups.Illustrative alkoxy groups are methoxy, ethoxy, propoxy, butoxy,isobutoxy, pentoxy, hexoxy and 2-ethylhexoxy; dialkoxy radicals, such asmethoxymethoxy or ethoxymethoxy and alkoxyaryloxy, such asethoxyphenoxy. The most preferred alkoxy groups are methoxy or ethoxy.

R is individually selected from the group consisting of aliphatic,alkyl, aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl organic andaromatic aryl groups. Most preferred are the methyl, ethyl, octyl,vinyl, allyl and phenyl groups.

R¹ is individually selected from the group consisting of X, aliphatic,alkyl, alkenyl and aromatic aryl groups. Most preferred are methyl,ethyl, octyl, trifluoropropyl, vinyl and phenyl groups.

When the siloxane polymer of formula (1) has an average of more than twocondensable or hydrolyzable groups per molecule which are self-catalytic(or which may alternatively, perhaps be referred to as self-activating),it is not necessary to have the self-catalytic crosslinker presentseparately to form a crosslinked polymer. The condensable orhydrolyzable groups on the different siloxane molecules can react witheach other to form the required crosslinks.

The siloxane polymer (a) can be a mixture of different kinds ofmolecules, for example, long chain linear molecules and short chainlinear or branched molecules. These molecules may react with each otherto form a crosslinked network. Such siloxanes, which can take the placeof more conventional crosslinkers, are illustrated by low molecularweight organosilicon hydrides, such as polymethylhydrogensiloxane, lowmolecular weight copolymers containing methylhydrogensiloxy anddimethylsiloxy groups, —(OSi(OEt)₂)—, (ethylpolysilicate),(OSiMeC₂H₄Si(OMe)₃)₄ and (OSi-MeON═CR′₂)₄, where Me is methyl and Et isethyl.

Advantageously, the siloxane polymer (a) also comprises mixtures ofsiloxane polymers of formula (1), exemplified by, but not limited to,mixtures of hydroxylsiloxy-hydroxysiloxy terminated siloxanes and ofα,ω-bis(triorganosiloxy) terminated siloxanes, mixtures ofα,ω-hydroxylsiloxy terminated siloxanes and of α-hydroxy,ω-triorganosiloxy terminated siloxanes, mixtures of α,ω-dialkoxysiloxyterminated siloxanes and of α,ω-bis(tri-organosiloxy) terminatedsiloxanes, mixtures of α,ω-dialkoxysiloxy terminated siloxanes and ofα,ω-hydroxysiloxy terminated siloxanes, mixtures of α,ω-hydroxysiloxyterminated siloxanes and of α,ω-bis(triorganosiloxy) terminatedpoly(diorgano)(hydrogenorgano)siloxane copolymers. The siloxane polymeras described herein can also comprise mixtures of siloxane polymers offormula (1) as described above with liquid, branched methylpolysiloxanepolymers (“MDT liquids”) comprising a combination of recurring units ofthe formulae:

(CH₃)₃SiO_(1/2)  (“M”)

(CH₃)₂SiO  (“D”)

CH₃SiO_(3/2)  (“T”)

and containing from 0.1 to 8% hydroxyl groups. The liquids may beprepared by co-hydrolysis of the corresponding chloro- oralkoxy-silanes, as described, for example, in U.S. Pat. No. 3,382,205.The proportion of MDT liquids added should not exceed 50 parts,preferably of 1 to 20 parts by weight, per 100 parts by weight of thepolymer of Formula (1), to achieve improved physical properties andadhesion of the resultant polymers. The siloxane polymer as hereindescribed can also comprise mixtures of siloxane polymers of Formula (1)with liquid or solid, branched methylsiloxane polymeric resinscomprising a combination of recurring units of the formulae:

(CH₃)₃SiO_(1/2)  (“M”)

(CH₃)₂SiO  (“D”)

CH₃SiO_(3/2)  (“T”)

SiO_(4/2)  (“Q”)

and containing from 0.1 to 8% hydroxyl groups, the liquids may beprepared by co-hydrolysis of the corresponding chloro- oralkoxy-silanes, as described, for example in U.S. Pat. No. 2,676,182.The MDTQ liquid/resin may be added in a proportion not exceeding 50parts, preferably of 1 to 10 parts by weight, per 100 parts by weight ofthe polymer of Formula (1) to improve physical properties and adhesionof the resultant polymers. MDTQ liquids/resins can also be mixed withMDT liquids and the polymers of Formula (1).

The at least one self-catalytic crosslinker (b) reactive with (a) toform reaction product (i) is present in the amount of 1 to 5 parts byweight per 100 parts of siloxane polymer. The term “self-catalyticcrosslinker” is well known and means a molecule that has at least onegroup serving as the catalytic species (or activating species). Hence,an alternative name for such a cross-linker might be a “self-activatingcross-linker”, if preferred. For example, a molecule that has at leastone functional group that reduces the energy activation level necessaryfor an e.g. hydroxyl functional groups on a siloxane polymer to condenseforming a cross linked polymer.

While in certain circumstances only one self-catalytic crosslinker maybe needed to produce an elastomer having the desired physicalproperties, those skilled in the art will recognize that two or moreself-catalytic crosslinkers may be added to the reaction mixture toachieve excellent results. In addition, the self-catalytic crosslinkeror crosslinkers may be added with a conventional catalyst. However,adding the self-catalytic crosslinker with a conventional catalyst isnot required and the compositions contemplated herein may, in fact, befree of said conventional catalysts.

Typical self-catalytic crosslinkers (or alternatively self-activatingcross-linkers) include tri or tetra functional compounds, such asR—Si-(Q)₃ or Si-(Q)₄, where Q is carboxylic, OC(O)R⁴, e.g., acetoxy andR⁴ is an alkyl group of 1 to 8 carbon atoms inclusive, preferablymethyl, ethyl or vinyl. Other preferred Q groups are the hydroxylamines, ON(R⁴)₂, where each R⁴ is the same or different alkyl group of 1to 8 carbon atoms inclusive, e.g., ON(CH₂CH₃)₂. Q may also be an oximegroup, such as O—N═C(R⁴)₂, where each R⁴ is the same or different alkylgroup of 1 to 8 carbon atoms inclusive, e.g., O—N═C(CH₃)(CH₂CH₃).Further, Q may be an amine group, such as N(R⁵)₂, where R⁵ is the sameor different alkyl group of 1 to 8 carbon atoms inclusive or cyclicalkyl group, e.g., N(CH₃)₂ or NH(cyclohexyl). Finally, Q may be anacetamido group, NRC(0)R⁴, where R⁴ is an alkyl group of 1 to 8 carbonatoms inclusive, e.g. N(CH₃)C(O)CH₃.

In addition, partial hydrolysis products of the aforementioned compoundsmay also function as self-catalytic crosslinkers. This would includedimers, trimers, tetramers and the like, for example, compounds of theformula:

where Q and R⁴ are defined in the preceding paragraph.

Also useful as self-catalytic crosslinkers are those polymeric orcopolymeric species containing 3 or more (Q) sites located at eitherpendant or terminal positions or both on the backbone of apolydiorganosiloxane molecule. Examples of the pendent group includecompositions of the following formula:

where R⁴ is as indicated above and a is 0 or a positive integer and b isan integer greater than 2. In general, polymeric compositions havingeither pendent or terminal Q groups may be used herein, in particular,compounds of the formula:

Q_(3-n)R⁶ _(n)SiO(R⁶ ₂SiO)_(z)SiR⁶ _(n)Q_(3-n)

where n is 0, 1, 2 or 3, z is a positive integer, R⁶ is Q orindependently the same or different alkyl chain of 1 to 8 carbon atomsinclusive if there are at least three Q groups on the molecule. Q is asdescribed above.

Effective self-catalytic crosslinkers (for which an alternative name maybe self-activating cross-linkers) are those compounds which form tackfree elastomers when mixed with functional silicone polymers in theabsence of additional catalysts such as tin carboxylates or amines. Inthe self-catalytic crosslinkers, the acetoxy, oxime, hydroxyl amine(aminoxy), acetamide and amide groups catalyze the formation of Si—O—Sibonds in the reactions contemplated.

One skilled in the art would recognize that the starting polymer itselfcould be pre-endblocked with self-catalytic crosslinking moieties.Optionally, further self-catalytic crosslinkers can be added to suchcompositions.

The surfactant (c) may be selected from nonionic surfactants, cationicsurfactants, anionic surfactants, amphoteric surfactants or mixturesthereof. The surfactant (c) is present in our composition in an amountof 0.5 to 10 parts by weight of siloxane polymer (a) and is preferablypresent in the amount of 2 to 10 parts.

Most preferred are nonionic surfactants known in the art as being usefulin emulsification of polysiloxanes. Useful nonionic surfactants arepolyoxyalkylene alkyl ethers, polyoxyalkylene sorbitan esters,polyoxyalkylene esters, polyoxyalkylene alkylphenyl ethers, ethoxylatedamides and others. The surfactants useful herein may be furtherexemplified by TERGITOL® TMN-6, TERGITOL® 15S40, TERGITOL® 15S9,TERGITOL® 15S12, TERGITOL® 15S15 and TERGITOL® 15S20, and TRITON® X405produced by The Dow Chemical Company of Midland, Mich.; BRIJ® 30 andBRIJ® 35 produced by Croda (UK); MAKON® 10 produced by STEPAN COMPANY,(Chicago, Ill.); and ETHOMID® 0/17 produced by Akzo Nobel Surfactants(Chicago, Ill.). Specific non-ionic surfactants include ethoxylatedalcohols, ethoxylated esters, polysorbate esters, ethoxylated amides;polyoxypropylene compounds, such as propoxylated alcohols,ethoxylated/propoxylated block polymers and propoxylated esters;alkanolamides; amine oxides; fatty acid esters of polyhydric alcohols,such as ethylene glycol esters, diethylene glycol esters, propyleneglycol esters, glyceryl esters, polyglyceryl fatty acid esters, sorbitanesters, sucrose esters and glucose esters.

Cationic and anionic surfactants known in the art as being useful inemulsification of polysiloxanes are also useful as the surfactantherein. Suitable cationic surfactants are aliphatic fatty amines andtheir derivatives, such as dodecylamine acetate, octadecylamine acetateand acetates of the amines of tallow fatty acids; homologues of aromaticamines having fatty chains, such as dodecylanalin; fatty amides derivedfrom aliphatic diamines, such as undecylimidazoline; fatty amidesderived from disubstituted amines, such as oleylaminodiethylamine;derivatives of ethylene diamine; quaternary ammonium compounds, such astallow trimethyl ammonium chloride, dioctadecyldimethyl ammoniumchloride, didodecyldimethyl ammonium chloride and dihexadecyldimethylammonium chloride; amide derivatives of amino alcohols, such asbeta-hydroxyethylstearyl amide; amine salts of long chain fatty acids;quaternary ammonium bases derived from fatty amides of di-substituteddiamines, such as oleylbenzylaminoethylene diethylamine hydrochloride;quaternary ammonium bases of the benzimidazolines, such asmethylheptadecyl benzimidazole hydrobromide; basic compounds ofpyridinium and its derivatives, such as cetylpyridinium chloride;sulfonium compounds, such as octadecylsulfonium methyl sulphate;quaternary ammonium compounds of betaine, such as betaine compounds ofdiethylamino acetic acid and octadecylchloromethyl ether; urethanes ofethylene diamine, such as the condensation products of stearic acid anddiethylene triamine; polyethylene diamines and polypropanolpolyethanolamines.

Cationic surfactants commercially available and useful herein includeARQUAD® T27W, ARQUAD® 16-29, ARQUAD® C-33, ARQUAD® T50, ETHOQUAD® T/13ACETATE, all manufactured by Akzo Nobel Surfactants (Chicago, Ill.).

Suitable anionic surfactants are carboxylic, phosphoric and sulfonicacids and their salt derivatives. The anionic surfactants useful hereinare alkyl carboxylates; acyl lactylates; alkyl ether carboxylates;n-acyl sarcosinate; n-acyl glutamates; fatty acid-polypeptidecondensates; alkali metal sulforicinates; sulfonated glycerol esters offatty acids, such as sulfonated monoglycerides of coconut oil acids;salts of sulfonated monovalent alcohol esters, such as sodiumoleylisethionate; amides of amino sulfonic acids, such as the sodiumsalt of oleyl methyl tauride; sulfonated products of fatty acidsnitriles, such as palmitonitrile sulfonate; sulfonated aromatichydrocarbons, such as sodium alpha-naphthalene monosulfonate;condensation products of naphthalene sulfonic acids with formaldehyde;sodium octahydroanthracene sulfonate; alkali metal alkyl sulphates,ether sulphates having alkyl groups of 8 or more carbon atoms andalkylarylsulfonates having 1 or more alkyl groups of 8 or more carbonatoms.

Anionic surfactants commercially available and useful herein includePOLYSTEP® A4, A7, A11, A15, A15-30K, A16, A16-22, A18, A13, A17, B1, B3,B5, B11, B12, B19, B20, B22, B23, B24, B25, B27, B29, C-OP3S;ALPHA-STEP® ML40, MC48; STEPANOL™ MG; all produced by STEPAN CO.,Chicago, IL; HOSTAPUR® SAS produced by HOECHST CELANESE; HAMPOSYL® C30and L30 produced by W.R. GRACE & CO., Lexington, Mass.

Suitable amphoteric surfactants are glycinates, betaines, sultaines andalkyl aminopropionates. These include cocoamphglycinate,cocoamphocarboxy-glycinates, cocoamidopropylbetaine, lauryl betaine,cocoamidopropylhydroxysultaine, laurylsulataine andcocoamphodipropionate.

Amphoteric surfactants commercially available and useful herein areREWOTERIC® AM TEG, AM DLM-35, AM B14 LS, AM CAS and AM LP produced bySHEREX CHEMICAL CO., Dublin, Ohio.

Specific silicone surfactants which improve high temperature stabilityinclude branched or linear polyoxyalkylenes. Specific fluorosurfactantsinclude those selected from anionics (such as carboxylates andsulfonics), non-ionics and amphoterics.

The selection of the surfactant in the composition herein alsoinfluences the clarity of the elastomeric film resulting from theevaporation of water from the dispersion. To obtain clear elastomersfrom silicone lattices, the refractive index must be matched in thefinal film between the crosslinked siloxane phase and thesurfactant/residual water phase. The term “crosslinked siloxane phase”refers to the plurality of crosslinked siloxane particles remainingafter water has evaporated to form an elastomeric film. The term“surfactant/residual water phase” refers to amount of residualsurfactant and water remaining in the elastomeric film after theevaporation of substantially all the water from the dispersion.

In addition to adding the surfactant to the siloxane polymer, themixture also includes a predetermined amount of water. The water ispresent in the mixture in an amount of 0.5 to 30 parts by weight ofsiloxane polymer and is preferably present in the amount of 2 to 10parts. Water may also be added after mixing, in any amount, to dilutethe gel phase.

The reaction product (i) may additionally comprise one or more additivessuch as in-situ resin reinforcers such as methyltrimethoxy silane,vinyltrimethoxy silane, tetraethyl orthosilicate (TEOS), normalpropylorthosilicate (NPOS) may be added with the self-catalyzingcrosslinker. It is believed that adding in situ resin reinforcers to thepolydiorganosiloxane/self-catalytic crosslinker mixture forms an in-situresin having a highly branched and crosslinked structure, which resultsin improved physical properties of the elastomer, particularly thetensile, elongation and hardness properties. It also results in improvedclarity of the resulting elastomer.

The reaction product (i) is produced by mixing the above components at asufficiently high shear to transform the mixture into a gel phase and bythen diluting the gel with water to the desired silicone content.

The reaction product of (a) a siloxane polymer having at least two —OHgroups per molecule, or polymer mixture having at least two —OH groupsper molecule, having a viscosity of between 5,000 to 500,000 mPa·s at21° C., and (b) at least one self-catalysing crosslinker reactive with(a), additionally comprising (c) a surfactant and (d) water; typicallycomprises, excluding additives (i.e. on the basis that the (product of(a)+(b))+(c)+(d) is 100% by weight), 70 to 90% by weight of the reactionproduct of (a)+(b), 3 to 10% by weight of (c) and 7 to 20% by weight ofcomponent (d). Alternatively, excluding additives (i.e. on the basisthat the (product of (a)+(b)+(c)+(d) is 100% by weight), 80 to 90% byweight of the reaction product of (a)+(b), 3 to 8% by weight of (c) and7 to 15% by weight of component (d). The cross-linked polysiloxanedispersion composition will typically comprise from 30 to 80 wt. %,alternatively 30 to 60 wt. %, alternatively 35 to 50 wt. % of reactionproduct (i) as hereinbefore described.

The liquid applied silicone-based air and water barrier compositionherein also comprises component (ii) one or more rheology modifiers inan amount of from 0.25 to 5 wt. % of the composition. Any suitablerheology modifiers may be present in the composition. For example, theymay be selected from one or more of the following, associativethickeners such as HASE materials and hydrophobe modified ethoxylatedurethanes (HEURs). Other rheology modifiers which may be utilisedinclude for the sake of example, hydroxyethyl celluloses (HECs), alkaliswellable emulsions (ASEs), suitable styrene-maleic anhydrideterpolymers (SMATs) as well e.g. natural and modified natural materials,such as, for example starch, modified starch, proteins, and modifiedproteins, dimeric and trimeric fatty acids and/or imidazolines.

HASE polymers are commercially important as associative thickener typerheology modifiers in aqueous paints and coatings. They are dispersionsof water-insoluble acrylic polymers in water which may be rendered watersoluble by neutralising acid groups on the polymer chain and alsocontain long-chain hydrophobic groups, sometimes referred to as“hydrophobes”. Typically, they are aqueous dispersions of copolymers of

(i) acylate ester or methacrylate ester monomers such as methylmethacrylate ethyl acrylate, butyl acrylate, or ethylhexyl acrylate);

(ii) methacrylic acid, acrylic acid, or itaconic acid; and

(iii) monomers containing long chain hydrophobic groups such as anethylenically unsaturated polyethylene oxide (polyEO) macromonomer, e.g.an alkylated ethoxylate monomer, preferably an alkylated ethoxylateacrylate or methacrylate.

The alkylated chains may be in the range of, for the sake of example,C10 to C25, alternatively C12 to C20.

For example, the following commercially available HASEs from the DowChemical Company contain polymerized units of ethyl acrylate andmethacrylic acid monomers with hydrophobes attached, include ACRYSOL™DR-6600, ACRYSOL™ DR-5500, ACRYSOL™ RM-7 ACRYSOL™ TT-615, ACRYSOL™ DR-72and ACRYSOL™ TT-935. Other commercially available HASEs include ACRYSOL™Primal HT-400, ACULYN™ 88,

ACULYN™28, ACULYNL™ 88 and Romax® 7011 from the Dow Chemical Company,RHEOTECH™ 4800 from Coatex.

Hydrophobe modified ethoxylated urethanes (HEURs) associative thickenertype rheology modifiers are widely used in waterborne coatings for theirdesirable rheological and application properties. The hydrophobicallymodified alkylene oxide urethane polymer is a polyethylene oxide,polypropylene oxide, or polybutylene oxide urethane polymer, preferablya polyethylene oxide urethane polymer modified with suitable thehydrophobes and may be prepared by e.g. reacting a diisocyanate; a watersoluble polyalkylene glycol; and a capping agent comprising thehydrophobe. The hydrophobes are then introduced by end-capping thisisocyanate terminated prepolymer with e.g. hydrophobic alcohols oramines.

ASE-thickeners are similar in polymer structure to HASE thickeners butdo not generally contain the hydrophobe groupings, i.e. they aredispersions of insoluble acrylic polymers in water which have a highpercentage of acid groups distributed throughout their polymer chains.When the acid groups are neutralized, the salt that is formed is‘hydrated’ the salt either swells in aqueous solutions or becomescompletely water soluble. As the concentration of neutralized polymer inan aqueous formulation increases, the swollen polymer chains start tooverlap, until they ‘tangle up’. It is this overlapping and tanglingthat causes viscosity to increase. Again, the concentration of acidgroups, the molecular weight and degree of crosslinking of the polymerare important in determining rheology and thickening efficiency.Examples include ACRYSOL™ ASE-75.

Hydroxyethyl cellulose polymers (HEC) are nonionic, water-solublepolymer that can thicken, suspend, bind, emulsify, form films,stabilize, disperse, retain water, and provide protective colloidaction. They are readily soluble in hot or cold water and can be used toprepare solutions with a wide range of viscosities. Examples includeNatrosol® 250 HBR.

For example, the rheology modifiers may be one or more hydrophobicallymodified alkali swellable emulsions (HASEs), one or more alkaliswellable emulsions (ASEs), one or more hydrophobe modified ethoxylatedurethanes (HEURs) and/or one or more hydroxyethyl celluloses (HECs). oneor more styrene-maleic anhydride terpolymers (SMATs) and/or mixturesthereof such as a mixture of a HASE, an ASE and/or a HEC.

The liquid applied silicone-based air and water barrier composition ashereinbefore described also comprises an acidic pH stable colloidalsilica. In general, colloidal silica particles are stable in between pH2 and 4 and at pH values>8.0 but are unstable in the pH range of from 3to 7 which without being bound to current theory is thought to be due tothe colloidal silica undergoing condensation in said pH range. In thepresent application the fact that the colloidal silica is “acidic pHstable” is intended to mean that the colloidal silica concerned isstable across the entire pH range of from 2 to 11. Hence, the acidic pHstable colloidal silica is a colloidal silica which is pH stable acrossthe pH range of from 2 to 11. The means of pH stabilisation is notessential for the application herein but, for example, the acidic pHstable colloidal silica may be largely charge stabilized with Al³⁺ ionsoptionally in the presence of a small amount of Na⁺ and K⁺ ions. Incomparison non-acidic pH grade silicas are generally believed to bestabilized by Na⁺ or K⁺ or NH₄ ³⁰ ions. Provided the colloidal silica isacidic pH stable it may be of any suitable mean particle size, forexample it may have a mean particle size of from 1 to 100 nm,alternatively from 1 to 75 nm, alternatively from 1 to 50 nm,alternatively from 1 to 25 nm, alternatively from 5 to 20 nm. Likewise,provided the colloidal silica is acidic pH stable it may be of anysuitable specific surface area, for example it may have a specificsurface area of from 100 to 500 m²/g, alternatively of from 125 to 450m²/g, alternatively of from 150 to 350 m²/g, alternatively of from 150to 300 m²/g which values may be determined by several methods includingby titration.

Component (iii) the acidic pH stable colloidal silica is present in thecomposition in an amount of from 15 to 30 wt. % of the composition,alternatively 17.5 to 30 wt. % alternatively 17.5 to 27.5 wt. %,alternatively from 17.5 to 25 wt. % of the composition.

Stabilizers may also be added to the composition. These may comprise anyan aminosilane containing polymer or neat aminosilane. Neat aminosilanesinclude compounds of the formula

(R⁴O)_(3-n)R⁴ _(n)nSiQ¹NR⁴ _(y)H_(2-y)

where n and y are independently 0, 1 or 2; R⁴ is the same or differentalkyl chain of 1 to 8 carbon atoms inclusive, Q¹ is (CH₂)_(z) or{(CH₂)_(z)N(R⁴)}_(w), where z is an integer from 1 to 10 and w is from 0to 3 inclusive.

Polymeric amino silanes may also be used in the composition herein, suchas reaction products of silanol functional siloxane liquids andaminosilanes or silanol functional siloxane liquids and alkoxysilanesand aminosilanes. For example, one useful polymeric amino siloxaneparticularly useful has the formula:

where z is from 3 to 40.

The coating composition as hereinbefore described may further includeone or more of the following additives: fillers other than (iii) above,solvents; pigments/colorants, defoamers; preservatives, such asbiocides, mildewcides, fungicides, algaecides, and combinations thereof;buffers, such as 2-amino-2-methyl-1-propanol, commercially sold asAMP-95, fire retardants, coalescents, disinfectants, corrosioninhibitors, antioxidants, antifoams and biocides flow agents; levelingagents; antifreeze materials, such as polypropylene glycol andadditional neutralizing agents, such as hydroxides, amines, ammonia, andcarbonates.

Optionally the liquid applied silicone-based air and water barriercomposition may also comprise one or more fillers other than (iii)above. Suitable fillers include, for the sake of example, fumed silicaprecipitated silica, semi-reinforcing agents, such as diatomaceous earthor ground quartz. Nonsiliceous fillers may also be added, such as,calcium carbonate, hydrated alumina, magnesium hydroxide, carbon black,titanium dioxide, aluminium oxide, vermiculite, zinc oxide, mica,talcum, iron oxide, barium sulphate, slaked lime, kaolin, calcinedkaolin, wollastonite, and hydroxyapatite.

Other fillers which might be used alone or in addition to the above,include aluminite, calcium sulphate (anhydrite), gypsum, calciumsulphate, magnesium carbonate, clays such as aluminium trihydroxide,graphite, copper carbonate, e.g., malachite, nickel carbonate, e.g.,zarachite, barium carbonate, e.g., witherite and/or strontium carbonate,e.g., strontianite; aluminium oxide, silicates from the group consistingof olivine group; garnet group;

aluminosilicates; ring silicates; chain silicates; and sheet silicates.The olivine group comprises silicate minerals, such as, but not limitedto, forsterite and Mg₂SiO₄. The garnet group comprises ground silicateminerals, such as, but not limited to, pyrope; Mg₃Al₂Si₃O₁₂; grossular;and Ca₂Al₂Si₃O₁₂. Aluminosilicates comprise ground silicate minerals,such as, but not limited to, sillimanite; Al₂SiO₅; mullite;3Al₂O₃.2SiO₂; kyanite; and Al₂SiO₅. The ring silicates group comprisessilicate minerals, such as but not limited to, cordierite andAl₃(Mg,Fe)₂[Si₄AlO₁₈]. If necessary, liquid alkoxysilanes which aresoluble in the siloxane polymer (a) may also be added with the filler tocompatibilise the filler with the siloxane polymers.

The selection and addition of particular fillers to our compositions,such as certain types of silicas, may improve the physical properties ofthe resulting elastomer, particularly tensile properties, elongationproperties, hardness and heat stability.

Typically the filler(s), when present are present in an amount of from10 to 200 weight parts of filler per 100 wt. parts of siloxane polymer(a), alternatively from 15 to 100 weight parts of filler per 100 wt.parts of siloxane polymer (a). Hydrophobing agents may be provided totreat the aforementioned filler(s) to render them hydrophobic andtherefore more easily mixed with reaction product (i) the hydrophobingagents may be for example silanes, e.g., alkoxy silanes, silazanes andor short chain (2-20) organopolysiloxanes or alternatively stearates orthe like.

It is envisaged to have the opportunity to provide colour tinted liquidapplied silicone-based air and water barrier composition which dry orcure to colour tinted coatings for reasons of architectural aestheticsso that such colour tinted coatings provides improved “hiding” ofunderlying components of the building. The shelf-life increase caused byusing the acidic pH stable silica described herein circumnavigateprevious limitations in supply chain options, geographic distribution,production scheduling, and ultimately coating performance.

The liquid applied silicone-based air and water barrier composition asdescribed herein may therefore also include colorants containingcoloured pigments that provide tint to coating compositions. The pigmentparticles contained in the formulation are white and non-white pigments.The colorant particles provide any colour including white to the coatingcomposition. Colorant particles include coloured pigments, whitepigments, black pigments, metal effect pigments, and luminescentpigments such as fluorescent pigments and phosphorescent pigments. Theterm “colorant particles”, as used herein includes white pigmentparticles such as titanium dioxide, zinc oxide, lead oxide, zincsulfide, lithophone, zirconium oxide, and antimony oxide. Examples ofcolours for the pigmented polymer composition include black, magenta,yellow, and cyan, as well as combinations of these colours such asorange, blue, red, pink, green, and brown. Other suitable colours forthe pigmented polymer composition include fluorescent colours; metalliccolours such as silver, gold, bronze, and copper; and pearlescentpigments. These colours are obtained by employing one or more differenttypes of colorant particles.

The colorant particles include inorganic colorant particles and organiccolorant particles. Typically, the colorant particles have averageparticle diameters in the range of from 10 nm to 50 μm, preferably inthe range of from 40 nm to 2 μm.

Suitable inorganic colorant particles include, but are not limited to,titanium dioxide pigments, iron oxide pigments such as goethite,lepidocrocite, hematite, maghemite, and magnetite; chromium oxidepigments; cadmium pigments such as cadmium yellow, cadmium red, andcadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuthvanadate molybdate; mixed metal oxide pigments such as cobalt titanategreen; chromate and molybdate pigments such as chromium yellow,molybdate red, and molybdate orange; ultramarine pigments; cobalt oxidepigments; nickel antimony titanates; lead chrome; blue iron pigments;carbon black; and metal effect pigments such as aluminium, copper,copper oxide, bronze, stainless steel, nickel, zinc, and brass.

Suitable organic colorant particles include, but are not limited to, azopigments, monoazo pigments, diazo pigments, azo pigment lakes,β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments,diazo condensation pigment, metal complex pigments, isoindolinone, andisoindoline pigments, polycyclic pigments, phthalocyanine pigments,quinacridone pigments, perylene and perinone pigments, thioindigopigments, anthrapyrimidone pigments, flavanthrone pigments, anthanthronepigments, dioxazine pigments, triarylcarbonium pigments, quinophthalonepigments, and diketopyrrolo pyrrole pigments.

As previously discussed the improvement is significant given theincreasingly desired wish from the industry of tinting such SWBEcompositions using liquid based pigment compositions. The compositionmay also comprise one or more pigments, such as carbon black or titaniumdioxide, and may also be added as fillers. Since these fillers are onlyintended to affect the color of the cured silicone latex elastomer, theyare typically added at 0.1 to 20 weight parts, preferably from 0.5 to 10weight parts, per 100 weight parts of siloxane polymer. Titanium dioxidehas been found to be particularly useful as an ultraviolet lightscreening agent.

Hence, a composition as hereinbefore described might comprise for thesake of example 30-80 wt. % of SWBE (i)

0.25 to 5 wt. % of one or more rheology modifiers (ii), such ashereinbefore described, alternatively HASEs ASEs, HECs, HEURs, SMATsand/or mixtures thereof;15 to 30 wt. % of an acidic pH stable colloidal silica; and0 to 10% wt. % of stabilizer(s) (iv); as well as a selection of otheradditives, such as for the sake of example, pigments and/or colorants,water, surfactant and/or antifoam with the total weight % of thecomposition being 100%.

The SWBE-based air barrier composition as hereinbefore described hasshelf-life stability as defined by maintaining a viscosity of less than(<) 100,000 mPa·s after greater than or equal to (≥) 7 weeks of 50° C.heat age testing, which corresponds to ≥15 months at room temperatureand thereby provides:

1) effective stabilization of the formulations for ≥15 months,2) the opportunity for point of sale tinting with aqueous dispersions,3) the opportunity for point of manufacture tinting with aqueousdispersions, whilst maintaining air and water barrier properties.

The compositions as described above are prepared by first makingreaction product (i), by first mixing siloxane polymer (a) and theself-catalysing crosslinker (b) and then introducing water (d) andsurfactant (c) to the preformed mixture of (a) and (b) and mixing (a) to(d) together until a high solids gel phase is formed. Any type of mixingequipment may be used including low shear mixing equipment, such asTurrello™, Neulinger™ or Ross™ mixers. The other ingredients of thecomposition may be introduced during the preparation of the pre-cureddispersion or alternatively may be added into the composition in anysuitable order prior to use and after mixing, the resulting compositionmay be diluted with water to the desired silicone content.

Those skilled in the art will recognize that these crosslinked, oil inwater dispersions may be prepared in other ways. For instance, thesiloxane polymer and self-catalytic crosslinker mixture may be added toa surfactant and water solution and then emulsified using colloid mills,homogenizers, sonolaters or other high shear devices as described inU.S. Pat. Nos. 5,037,878 and 5,034,455. The dispersion may be formed byeither a batch process, as described above, or a continuous process. Ifa continuous process is used, then a low shear dynamic mixer or staticmixer is preferred.

The composition as hereinbefore described may be applied onto a suitablesubstrate by any suitable method. For example, the liquid coating may bespray-applied, brushed, rolled, trowelled or otherwise coated onto asubstrate although spraying techniques are preferred. Once applied as acoating on the substrate the composition will form an elastomeric filmupon the evaporation of water although it is to be noted that no curereaction takes place upon application to a substrate the coating merelydries on the substrate surface, typically through water evaporation.Evaporating water from the cross-linked polysiloxane dispersioncomposition after the cross-linked polysiloxane dispersion compositionis applied results in the formation of a silicone latex elastomer on thesubstrate. The step of evaporation of water may be performed underambient, or atmospheric conditions at the location of the substrate whenthe cross-linked polysiloxane dispersion composition is applied.Alternatively, the step of evaporation of water may be performed underartificially heated conditions, produced by one or more heaters. Theresulting coating is preferably vapour permeable, alternatively it isvapour permeable.

The composition herein may be used as a vapour permeable, air and waterbarrier on any suitable substrate, such as for example masonrysubstrates, such as concrete block, fluted block, brick, stucco,synthetic stucco, poured concrete, precast concrete, insulation finishsystems (EIFS), shotcrete, gypsum as well as gypsum board, wood, plywoodand any other interior surfaces requiring said barrier coating. Thesubstrate may be located on either the interior or exterior of loadbearing supports of a wall assembly. Indeed, the substrate may be theaforementioned load bearing support, e.g., a concrete masonry unit(CMU). Before the cross-linked polysiloxane dispersion compositiondescribed above is dried, the wall assembly comprises cross-linkedpolysiloxane dispersion composition disposed on the substrate asdescribed above. However, after the cross-linked polysiloxane dispersioncomposition is dried, the wall assembly comprises an air and waterbarrier coating which is preferably vapour permeable, alternatively avapour permeable, air and water barrier coating formed from drying orevaporating the liquid applied silicone-based air and water barriercomposition described above.

The liquid applied, air and water barrier coating composition ashereinbefore described may be applied at a wet thickness of from 20 mil(0.508 mm) to 50 mil (1.27 mm), or from 20 to 60 mil (1.524 mm) anddries subsequent to application to a dry thickness of from 10 mil (0.254mm) to 25 mil (0.635 mm), or from 10 to 30 mil (0.762 mm). Depending ontemperature, humidity and wind conditions, the average drying time ofthe composition is from about 4 to 12 hours and full adhesion andphysical properties will be present after only a few days.

The liquid applied, air and water barrier coating composition ashereinbefore described, once dried on a substrate, meets therequirements of ASHRAE 90.1-2010 for ASTM E2178-11, Standard Test Methodfor Air Permeance of Building Materials, having an Air Permeance (L/sper m²) of less than 0.006 at a differential pressure of 75 Pa atthicknesses of both 10 mil (0.254 mm) and 15 mil (0.381 mm).

A liquid applied, air and water barrier coating composition ashereinbefore described, once dried, when vapour permeable, has a WaterVapour Transmission of greater than 7 US Perm (400.49 ng·s⁻¹m⁻² Pa⁻¹),greater than 10 US Perm (572.135 ng·s⁻¹m⁻² Pa⁻¹), or greater than 15 USPerm (858.2035 ng·s⁻¹m⁻² Pa⁻¹) according to the Dry Cup Desiccant Methodof ASTM E96/E96M-10 for both the 10 mil (0.254 mm) and 15 mil (0.381 mm)thicknesses, Standard Test Method for Water Vapour Transmission rate ofMaterials and in accordance with Water Vapour Transmission Wet Cup WaterMethod of ASTM E96/E96M-10, Standard Test Method for Water VapourTransmission rate of Materials of greater than 20 US Perm (1144.27ng·s⁻¹m⁻² Pa⁻¹) greater than 24 US Perm (1373.12 ng·s⁻¹m⁻² Pa⁻¹),greater than 25 US Perm (1430.3375 ng·s⁻¹m⁻² Pa⁻¹), or greater than 30US Perm (1716.41 ng·s⁻¹m⁻² Pa⁻¹) for coatings of 10 mil (0.254 mm)thickness and for coatings of 15 mil (0.381 mm) thicknesses.

Furthermore, the liquid applied, air and water barrier coatingcomposition as hereinbefore described, once dried passes the SelfSealability (Head of Water) Test described in Section 8.9 of ASTMD1970-09.

Also given that the siloxane is pre-cured it was believed that suchcompositions would be unable to successfully pass tests such as the SelfSealability (Head of Water) Test described in Section 8.9 of ASTMD1970-09 because it was not expected that the film would be able toself-heal in order to maintain its integrity and prevent water ingressetc. In both cases the composition as hereinbefore described hasunexpectedly proven to meet the necessary requirements for these twomatters. Furthermore, the coating as described herein has the addedadvantage over many currently available air and water barrier coatingsin that it is compatible with other silicone-based products such asadhesives, caulks and sealants.

Hence, the present composition may be used as a vapour permeable, airand water barrier coating in any building requiring same, for example,cavity wall systems in climatic regions where the provision of air andwater barriers which are permeable to (water) vapour are 2 0 beneficialand when the structure of the cavity wall is designed appropriately. Asthe skilled man appreciates, cavity wall systems vary in structure toaccommodate the local climate, i.e., the relative positions of theinsulation and air and water barrier in the cavity wall system as thecoating is provided to enable the diffusion of water vapour through thecoating and is intended to be applied on a substrate with a view toprevent the risk of moisture getting trapped in the wall cavity. Thecomposition herein is particularly suited for environments in which highlevels of (water) vapour permeability are advantageous because of thesurrounding climate.

It is known that silicones have excellent overall durability, includingultraviolet radiation exposure on buildings. An air barrier needs towithstand a certain amount of ultraviolet radiation during the periodafter installation and before the exterior building façade is installed.Some air barriers have a limited exposure time before the manufacturerrecommends covering the air barrier with the building façade. As thecomposition herein is a silicone-based material the ultravioletdurability allows the air barrier to be exposed indefinitely to theatmosphere or for at least a long period of time which could enablegreater flexibility during construction or in the event of delays on thejobsite.

Whilst the majority of commercially available coatings cure to a minimum40 mil (1.016 mm) thickness and often require even thicker coatings, thecomposition herein may be coated on a substrate at a thickness of 10 mil(0.254 mm) to 30 mil (0.762 mm) and still meets all necessary tests aswill be noted in the following examples avoiding problems encounteredwith many commercial alternatives which require significantly thickercoatings (e.g., >50 mil (1.27 mm)) especially as it is recognised thatvery thick coatings of air and water barriers can interfere withdiffusion. It is to be noted that the present composition contains apre-cured polysiloxane network prior to application and as such thecoating is applied and merely dries on the substrate rather than havingthe additional need to cure. The composition as hereinbefore describedis suitable for providing an evenly distributed coating across the wholesurface of a substrate, even when said substrate has an uneven surfaceand/or is porous.

The coating composition as described herein, when applied onto asubstrate, provides substrates with long-term protection from air andwater infiltration, normal movement imposed by seasonal thermalexpansion and/or contraction, ultra-violet light and the weather. Itmaintains water protection properties even when exposed to sunlight,rain snow or temperature extremes. Indeed, the composition when testedin accordance with ASTM 1970-09, section 8.6 for low temperatureflexibility using a sample having a 15 mil (0.381 mm) coating thickness,passed the test proving that the composition, once applied, remainsflexible at low temperatures.

The liquid-applied air and water barrier coatings which are preferablyvapour permeable as herein described may be formed by applying a liquidapplied silicone-based air and water barrier composition onto a suitableinternal building construction surface. The liquid appliedsilicone-based air and water barrier compositions may be applied by anysuitable method e.g. by being rolled, painted, sprayed or trowelled ontosubstrates and resulting coatings become part of the structural wall(after typically being applied from the inside of the building) with theliquid-applied compositions drying or curing as a monolithic membraneon, in or around the building envelope.

Whilst historically these types of compositions are generally used withwalling systems not requiring fastener holes to avoid water penetrationtherethrough, this is unnecessary for compositions as hereinbeforedescribed as they unexpectedly have been found to reseal. Hence,compositions as hereinbefore described may also be used in situationswhere there is potential for mislapping or tearing, of the substratesduring installation.

One particular advantage over other products is that the coatingcomposition as described herein, when applied onto a substrate, may beexposed for an extended or even indefinite period of time prior to theapplication of exterior cladding due to their UV stability.

In one embodiment of the disclosure herein there is provided a wallassembly. The wall assembly described herein can be coated with a drycoating of the liquid applied silicone-based air and water barriercomposition, which is preferably vapour permeable, as an adhesive tobond elastomer material(s) to construction sheathing substrate(s), metalsubstrate(s) such as painted or unpainted aluminium substrates,galvanized metal substrate(s), wood framing substrate(s) and the like.Other suitable substrates include, for the sake of example, concrete,oriented strand board (OSB), exterior sheathing, preformed panels,plywood and wood or steel stud walls.

EXAMPLES

The present disclosure will now be described in detail by way of thefollowing Examples in which all viscosity measurements were taken atroom temperature (approximately 21° C.) using a Brookfield DV-III Ultra,Spindle 04, at 2 rpm.

Preparation of Composition

A crosslinked polysiloxane dispersion was prepared by introducing about2 parts by weight of

(where each R⁴ group is a methyl group) into 100 parts by weight of ahydroxyl dimethyl silyl terminated polydimethylsiloxane having aviscosity of 50,000 mPa·s at 21° C. using a recording Brookfieldviscometer with Spindle 3 at 2 rpm according to ASTM D4287-00(2010) in aTurrello mixer. 4 parts of a 1:1 solution of water and surfactant(TERGITOL™ TMN-10) were then added and the resulting mixture was mixeduntil a high solids emulsion gel was formed. The resulting pre-formedsilicone latex emulsion was then suitable for mixing with the otheringredients of the composition.

All the compositions used in the following examples and counter exampleswere prepared using the following composition with, unless otherwiseindicated, the only variables being the type and wt. % of colloidalsilica and the water which was varied dependent on the amount ofcolloidal silica present so that the total weight % of the compositionwas always 100%.

42.6 wt. % of the previously prepared crosslinked polysiloxanedispersion 1.44 wt. % of rheology modifiers (0.38 wt. % Aculyn™ 88(HASE) 0.81 wt. %, ACRYSOL™ ASE-75. (ASE) and 0.25 wt. % Natrosol® 250HBR (HEC))Colloidal silica in the amounts and types as defined in the tablesbelow; in combination with

-   -   12.7 wt. % ultrafine calcium carbonate    -   2.5 wt. % Dupont Ti-PURE® R-706 titanium dioxide pigment    -   0.8 wt. % non-ionic surfactant, Dow TERGITOL™ TMN-10    -   1.0 wt. % of antifoam,    -   0.8 wt. % propylene glycol    -   Balance to 100 wt. % was made up with water.

Three alternative types of silica were compared in the followingexamples and counter examples details of which are provided in Table 1below. Nalco® 1115 was obtained from Nalco Water Corporation. Ludox® FMand Ludox®AM were obtained from WR Grace Corporation.

TABLE 1 Silica Particle size Specific Surface Stable in pH grade (nm)Area (m²/g) range 3-7? Nalco ® 4 not provided by No 1115 SupplierLudox ® 5 390-480 No FM Ludox ® 12 228 Yes AM

The compositions were prepared using the following process:

The crosslinked polysiloxane dispersion, water, nonionic surfactant, andantifoam were mixed together for 10 minutes at 800 rpm and then 5minutes at 1200 rpm using a Caframo™ overhead mixer with a dispersingstyle impeller. The HEC was then slowly added over a 2 minute periodwhile mixing at 1200 rpm and then the resulting mixture was furthermixed for 5 minutes at 1600 rpm. The appropriate silica was added andmixing continued for a further 5 minutes at 1600 rpm. The calciumcarbonate and titanium dioxide were then introduced and the resultingmixture was further mixed for 15 minutes at 1600 rpm after which apremixture of HASE and ACRYSOL™ ASE-75 was slowly added over a 5 minuteperiod while mixing at 1200 rpm, finally propylene glycol was then addedfollowed by a further 5 minutes of mixing at 1200 rpm before AMP-95buffer was used to make the composition have a pH of between 10.1 and10.3, after which the final composition was de-aerated under vacuumusing a FlackTek SpeedMixer™ at 2000 rpm for 2 minutes and then filteredprior to use.

A variety of physical properties of samples of each composition preparedwere determined for both examples and comparative examples.

Water Vapour Transmission rate is the steady water vapor flow in unittime through unit area of a body, normal to specific parallel surfaces,under specific conditions of temperature and humidity at each surfaceand was tested according to the ASTM E96/E96M-10, Standard Test Method.

Nail sealability is determined using the Self Sealability (Head ofWater) Test described in Section 8.9 of ASTM D1970-09. It assesses thenail sealability requirements of bituminous roofing systems but is acommonly used standard for air barrier materials. It is an importanttest because elastomeric materials do not innately have a self-sealingproperty. All examples and counter examples prepared met or exceeded theacceptable values depicted in Table 2 below.

TABLE 2 Requirement Test Units Acceptable Value(s) Water Vapor ASTM E96US Perms >15 (>858.2) Permeability (Method B) (ng · s⁻¹ · m⁻² · Pa⁻¹ ₎Sag D 4400 Wet mils (mm) 40-60 (1.016-1.524) Resistance Color Y value —22-27 Tensile ASTM D 412 psi (kPa) >180 (>1241.1) Elongation ASTM D 412% >400 Adhesion D4541 - psi (kPa) >120 (>827.4) Concrete AdhesionD4541 - psi (kPa) >40 (275.8) Fiberglass mat gypsum Crack Bridging ASTMC1305 — Pass Nail ASTM D1970, — Pass Sealability Section 8.9

Historically, cross-linked polysiloxane dispersions have had shelf-lifeproblems as previously discussed. Samples are considered to haveexceeded their shelf life once the viscosity has exceeded 100,000 mPa·sat room temperature (approximately 21° C.). In order to determine theshelf-life of samples of each example and comparative prepared abovecompositions were subjected to the following in-house AcceleratedShelf-Life Aging Test:—

-   1. Add samples prepared according to procedure above into sealed    container, and place in oven at 50° C.-   2. Every 7 days remove samples from oven, cool to room temperature    (21° C.), and measure viscosity.-   3. Reseal container lid and return to oven for additional aging.-   4. Repeat steps 2 and 3 until samples reach >100,000 mPa·s at room    temperature-   5. Record viscosity value for each week that a sample is at or below    100,000 mPa·s at room temperature.-   6. It has been determined that a value of 6 weeks or greater defines    a shelf-life of 15 months or greater according to Arrhenius behavior    using a conservative Q10 factor of 2.1.

Viscosity measurements taken during the accelerated Shelf-Life AgingTest were done so using a Brookfield® DV-III Ultra, Spindle 04, at 2 rpmand room temperature (21° C.),

-   1. Let samples cool to room temperature (if at elevated    temperature). Remove lid.-   2. Mix samples by hand with tongue depressor before measuring-   3. Lower spindle until it touches bottom of container, then raise ¼    inch (0.635 cm).-   4. Start instrument and wait until steady state measurement is    obtained.

The silica type and silica concentration and time to reach a viscosityof 100,000 mPa·s at room temperature for each example are described inTable 3.

TABLE 3 Colloidal Silica Time to 100K concentration mPa · s ExampleSilica Type (wt. %) (weeks) E. 1 Ludox ®AM 23.1 11 E. 2 Ludox ®AM  11.4211 E. 3 Ludox ®AM 23.0 11 C. 1 Nalco ®1115 24.1 5 C. 2 Ludox ®FM 24.1 7C. 3 Nalco ®1115 23.0 4 C. 4 1:3 wt. ratio mix of 23.1(?) 6 Ludox ®AMand Nalco ®1115 C. 5 1:1 wt. ratio mix of 23.1(?) 6 Ludox ®AM andNalco ®1115 C. 6 3:1 wt. ratio mix of 23.1(?) 7 Ludox ®AM andNalco ®1115

It will be appreciated that the use of the acidic pH stable colloidalsilica in Examples 1 to 3 results in a significantly longer shelf-lifefor the product compared to compositions in which the acidic pH stablecolloidal silica is omitted.

1. A liquid applied, air and water barrier coating composition, theliquid coating composition comprising: (i) a crosslinked polysiloxanedispersion of: a reaction product of (a) a siloxane polymer having atleast two —OH groups per molecule, or a polymer mixture having at leasttwo —OH groups per molecule, and having a viscosity of between 5000 to500,000 mPa·s at 21° C., and (b) at least one self-catalyzingcrosslinker reactive with component (a), and additionally comprising (c)a surfactant and (d) water; (ii) one or more rheology modifiers in anamount of from 0.25 to 5 wt. % of the composition; and (iii) an acidicpH stable colloidal silica in an amount of from 15 to 30 wt. % of thecomposition; and optionally (iv) one or more stabilizers.
 2. The liquidcoating composition in accordance with claim 1, wherein the acidic pHstable colloidal silica (iii) is present in an amount of from 17.5 to 25wt. % of the composition.
 3. The liquid coating composition inaccordance with claim 1, wherein the one or more rheology modifiers (ii)comprises one or more hydrophobically modified alkali swellableemulsions, one or more alkali swellable emulsions, one or morehydrophobe modified ethoxylated urethanes, one or more hydroxyethylcelluloses and/or one or more styrene-maleic anhydride terpolymers. 4.The liquid coating composition in accordance with claim 1, wherein theone or more rheology modifiers (ii) consists of a mixture of one or morehydrophobically modified alkali swellable emulsions, one or more alkaliswellable emulsions and/or one or more hydroxyethyl celluloses.
 5. Theliquid coating composition in accordance with claim 1, wherein thecomposition further comprises one or more of the following additives:solvents; pigments/colorants; defoamers; preservatives; buffers; fireretardants; coalescents; disinfectants; corrosion inhibitors;antioxidants; antifoams; biocides; flow agents; leveling agents;antifreeze materials; and/or neutralizing agents.
 6. The liquid coatingcomposition in accordance with claim 1, wherein the composition furthercomprises an aqueous dispersion of pigments/colorants.
 7. The liquidcoating composition in accordance with claim 1, wherein the compositionhas a shelf-life of at least 15 months.
 8. A wall assembly having aninternal side and an external side, wherein either or both of the sidesis coated with a dried coating of the liquid coating composition inaccordance with claim
 1. 9. The wall assembly in accordance with claim8, wherein the liquid coating composition is applied on to a substrateat a wet thickness of from 20 mil (0.508 mm) to 60 mil (1.524 mm) anddries after application to a dry thickness of from 10 mil (0.254 mm) to30 mil (0.762 mm).
 10. The wall assembly in accordance with claim 8,wherein the the liquid coating composition, once dried on a substrate,meets the requirements of ASTM E2178-11, Standard Test Method for AirPermeance of Building Materials, having an Air Permeance (L/s per m²) ofless than 0.006 at a differential pressure of 75 Pa at thicknesses ofboth 10 mil (0.254 mm) and 15 mil (0.381 mm).
 11. The wall assembly inaccordance with claim 8, wherein the liquid coating composition, oncedried on a substrate, meets Water Vapour Transmission Dry Cup DesiccantMethod in accordance with ASTM E96/E96M-10, Standard Test Method forWater Vapour Transmission rate of Materials of greater than 7 US Perm(572.135 ng·s⁻¹m⁻² Pa⁻¹), for both 10 mil (0.254 mm) and 15 mil (0.381mm) thicknesses, and Water Vapour Transmission Wet Cup Water Method inaccordance with ASTM E96/E96M-10, Standard Test Method for Water VapourTransmission rate of Materials of 30 US Perm (1716.41 ng·s⁻¹m⁻² Pa⁻¹)for coatings of 10 mil (0.254 mm) thickness and greater than 24 US Perm(1373.12 ng·s⁻¹m⁻² Pa⁻¹) for coatings of 15 mil (0.381 mm) thickness.12. The wall assembly in accordance with claim 8, wherein the liquidcoating composition, once dried on a substrate, passes the SelfSealability (Head of Water) Test described in Section 8.9 of ASTMD1970-09.
 13. The wall assembly in accordance with claim 8, wherein theliquid coating composition has a substrate selected from the groupconsisting of construction sheathing substrates, metal substrates,galvanized metal substrates, wood framing substrates, concrete masonry,foam plastic insulated sheeting, exterior insulation, pre-formedconcrete, cast in place concrete wood framing, oriented strand board(OSB), exterior sheathing, preformed panels, plywood and wood or steelstud walls, roofing felting for roofing membranes, and non-permeablewall assemblies.
 14. The wall assembly in accordance with claim 8,wherein the dried coating is vapour permeable.
 15. A method ofincreasing the shelf stability of a liquid applied, air and waterbarrier coating composition, the method comprising: introducing (iii) anacidic pH stable colloidal silica in an amount of from 15 to 30 wt. % ofthe composition; into a liquid coating composition otherwise comprising:(i) a crosslinked polysiloxane dispersion of: a reaction product of (a)a siloxane polymer having at least two —OH groups per molecule, or apolymer mixture having at least two —OH groups per molecule, and havinga viscosity of between 5000 to 500,000 mPa·s at 21° C., and (b) at leastone self-catalyzing crosslinker reactive with component (a), andadditionally comprising (c) a surfactant and (d) water; and (ii) one ormore rheology modifiers in an amount of from 0.25 to 5 wt. % of thecomposition; and optionally (iv) one or more stabilizers.
 16. The methodin accordance with claim 15, wherein the shelf-stability of the liquidcoating composition is at least 15 months.
 17. The method in accordancewith claim 15, wherein the liquid coating composition further comprisesan aqueous dispersion of pigments/colorants.
 18. A method of treating awall assembly, having an internal side and an external side, the methodcomprising: applying the liquid coating composition in accordance withclaim 1 on either or both of the sides by spraying, brushing, orrolling.
 19. The method in accordance with claim 18, further comprisingevaporating water from the liquid coating composition after applicationto the side(s).
 20. The method in accordance with claim 18, wherein theliquid coating composition is applied on to a substrate at a wetthickness of from 20 mil (0.508 mm) to 60 mil (1.524 mm) and dries afterapplication to a dry thickness of from 10 mil (0.254 mm) to 30 mil(0.762 mm). 21-25. (canceled)